In the manufacture of integrated circuits, including dynamic random access memory (DRAM), tungsten (W) is frequently used as a gate conductor material. However, the integration of tungsten into semiconductor processing involves a number of significant challenges. For example, typical fabrication of a tungsten gate electrode stack involves forming a gate oxide layer on a silicon substrate such as by thermal oxidation or chemical vapor deposition (CVD). A subsequently deposited bulk tungsten film has a relatively poor adhesion to the gate oxide layer. Thus, an adhesion layer (i.e., a glue layer), such as tungsten silicide (WSi) or tungsten nitride (WN) is deposited onto the gate oxide layer prior to depositing the bulk tungsten film. However, the inventors have observed that the adhesion layer often exhibits unsatisfactory adhesion to the underlying oxide and the subsequently deposited bulk tungsten material and also fails to provide suitable resistivity of the gate stack.
Accordingly, the inventors have provided improved tungsten silicide nitride films and methods for depositing tungsten silicide nitride films useful, in a non-limiting example, for an adhesion layer in DRAM applications.